Carbohydrates (CHO) are a category of compounds derived from plant foods which provide one molecule of water with each carbon. Carbohydrates are an ideal source of energy for the body and are naturally occurring compounds that consist of carbon, hydrogen, and oxygen. Carbohydrates are produced by one of the most complex, vital, and amazing processes in the physical world: photosynthesis. Photosynthesis involves the conversion of carbon dioxide and water to sugars, which, along with starches and cellulose, are some of the more well known varieties of carbohydrate. Because they are an integral part of plant life, it is no wonder that carbohydrates are in most fruits and vegetables. And although they are not a dietary requirement in the way that vitamins or essential amino acids are.

Chemically, carbohydrates are organic molecules in which carbon, hydrogen, and oxygen bond together in the ratio: Cx(H2O)y, where x and y are whole numbers that differ depending on the specific carbohydrate to which we are referring. This is because they can be converted more readily into glucose, the form of sugar that's transported and used by the body, than can proteins or fats. Although some foods contain large quantities of carbohydrate nearly all foods (except fats) contain a mixture of carbohydrates, proteins and fats. So, most foods contain some amount of carbohydrate, however small.

Even so, a diet too high in carbohydrates can upset the delicate balance of your body's blood sugar level, resulting in fluctuations in energy and mood that leave you feeling irritated and tired. Animals (including humans) break down carbohydrates during the process of metabolism to release energy. It is better to balance your intake of carbohydrates with protein, a little fat and fiber. Simple sugars, refined carbohydrates, and low-fiber, complex carbohydrates represent a threat to health when they are consumed in inappropriate amounts such as may occur in low-soy, vegetarian diets where they are being eaten to replace the calories which would ordinarily come from protein.

Carbohydrates are an important part of any healthy diet. Eaten regularly, carbohydrates do not lead to weight gain, unless they are eaten to excess. After all, eating too much of anything and not burning it off through physical activity will lead to weight gain. The speed of digestion is determined by the chemical nature of the carbohydrate itself, and thus how "resistant" it is to the activity of the enzymes. A simple sugar is much less resistant than a starch, and is digested or metabolized much faster. Things that slow down digestion include: the presence of acid and the presence of soluble fiber.

Carbohydrate foods in their natural state have many benefits: They are high in fiber, low in fat, and a good source of vitamins. They can also be a good source of minerals, depending on the mineral content of the soil they were grown in. If you want to derive all the benefits of carbohydrates, you need to eat them in a right amount. The right amount of carbohydrates for most people is about 40% of their diet, with emphasis on the complex variety. More than 50% of the diet as carbohydrates or too many refined carbohydrates causes problems.

The Result of Excess Carbohydrate Intake

Carbohydrates in the right amount are beneficial. Too much of anything is bad for the body, and low-fat starchy foods are no exception. When sugars or starches become a larger percentage of our diet than best suits our individual biochemistry, carbohydrate toxicity occurs.

Excess carbohydrate also causes generalized vascular disease. The high-carbohydrate diet which is now so popular causes the pancreas to produce large amounts of insulin. Because insulin's action is to drive glucose into the cells, this results in chronic hyperglycemia, also called "high blood sugar." Excess insulin also causes hypertension and helps initiate the sequence of events in the arterial wall which leads to atherosclerosis and heart disease.

Adult onset diabetes is known to be greatly benefited by the adoption of a low carbohydrate diet, moderate in fat, which stresses the importance of a regular intake of sufficient protein. Excess carbohydrates upset the hormonal system and results in an imbalance favoring the type of "Eicosanoid" also known as "prostaglandins E-2" or "PGE-2".

Types of carbohydrates

Carbohydrates are one of the main energy booster nutrients that human body requires, in order to keep going. Carbohydrates can be broadly classified into three broad categories:

  1. Sugar or Simple Carbohydrates
  2. Simple carbohydrates are also known as sugars. They also exist in either a natural or refined form. Natural sugars are found in fruit and vegetables. Carbohydrates that contain only one sugar unit (Monosaccharides) or two sugar units (disaccharides) are referred to as simple sugars. Two of the most common Monosaccharides are glucose and fructose. Glucose is the primary form of sugar stored in the human body for energy and Fructose is the main sugar found in most fruits. Disaccharides have two sugar units bonded together. For example, common table sugar is sucrose. Refined sugars are found in: Biscuits, Cakes and Pastries, Chocolate, Honey and Jams, Jellies, Brown and White cane sugar, Pizzas prepared foods and Sauces, Soft drinks, Sweets and Snack bars. Simple carbohydrates (sugar) cause tooth decay.

  3. Starch or Complex Carbohydrates
  4. Starches are complex carbohydrates without taste or odor, which are granular or powdery in physical form. Complex carbohydrates are long chains of simple sugar units bonded together and for this reason the complex carbohydrates are often referred to as polysaccharides. Starch is the principal polysaccharide used by plants to store glucose for later use as energy. They are found naturally in foods and also refined in processed foods. Complex carbohydrates as natural starches are found in: bananas, barley, beans, brown rice, chickpeas, lentils, nuts, oats, parsnips, potatoes, root vegetables, sweet corn, whole grain cereals, and whole meal breads, whole meal cereals, whole meal flour, whole meal pasta, yams. Complex carbohydrates as refined starches are found in: biscuits, pastries and cakes, pizzas, sugary processed breakfast cereals, white bread, white flour, white pasta, white rice.

  5. Fiber
  6. Fiber comes from plant foods so there is no fiber in animal products such as milk and other dairy products, eggs, meat, poultry, and fish. Fiber is the indigestible part of plant foods, including fruits, vegetables, whole grains, nuts, and legumes. When you consume dietary fiber, most of it passes through the intestines and is not digested.

    Good sources of dietary fiber include:
    • Beans and legumes: black beans, kidney beans, pintos, chick peas (garbanzos), white beans, and lentils.

    • Fruits and vegetables including apples, corn, beans and those with edible seeds for example, berries

    • Nuts including Peanuts, walnuts and almonds are a good source of fiber and healthy fat, but watch portion sizes, because they also contain a lot of calories in a small amount.

    • Whole grains include whole wheat pasta, whole grain cereals, and whole grain breads

Why do we need Carbohydrates?

Carbohydrate is a rich source of vitamins, which the body needs for a host of circulatory, immune, endocrine and other bodily functions as well as healthy cell growth and repair.

  • Carbohydrate is also the primary energy source of brain, nervous tissue, retina, kidney, and red blood cells.

  • Carbohydrates are also rich in protective phytochemicals, the newly discovered semi-essential micronutrients that protect against serious disease.

  • Carbohydrates are particularly a good source of B-complex vitamins which are very valuable for women.

  • Carbohydrates can be stored in the muscles for exercise

  • Carbohydrates provide lots of vitamins, minerals and fiber

  • Carbohydrates supply the main source of energy for the body

  • Carbohydrates which yield glucose are nutritionally important because glucose is the preferred fuel source of tissues.

  • Good health is essential for efficient weight loss. A sluggish body, lacking adequate nutrition, does not lose weight as fast as a healthy body.

How much carbohydrate do we need?

Each gram of carbohydrate provides 4 calories. You need anywhere from 40-60% of your calories from carbohydrate. There is no specific Recommended Daily Allowance (RDA) for carbohydrate. Glucose is more efficiently oxidized than fatty acids of equal carbon chain length and can be utilized under both aerobic and anaerobic conditions. Consequently, a minimum of 50% of total energy consumed should be digestible carbohydrate. The energy value of one gram of carbohydrate is 4 kilocalories. In contrast to digestible carbohydrate, dietary fiber and other indigestible carbohydrates yield only minimal energy from intestinal microbial fermentation. Metabolism of fermentable fiber yields short chain fatty acids which are absorbed by the colon. Butyrate is utilized within the colonocyte while propionate and acetate are absorbed and transported to muscle and liver, respectively. Fermentable fiber provides approximately 2 kcal/g of energy. Indigestible components of fiber benefit the intestinal tract by facilitating transport of nutrients and waste which lowers intralumenal pressure and promotes regularity.

Whole grains provide complex carbohydrate and tend to have more nutrients and fiber than refined grains. Eating plenty of whole grains may reduce your risk of heart disease.

Effects of Carbohydrate on cardiovascular disease

There are a variety of ways in which a high carbohydrate diet might be protective of cardiovascular disease risk:

  • Displacement of nutritionally disadvantageous components of the diet for e.g. saturated animal fat.

  • Fermentable carbohydrate in the colon produces absorbable short chain fatty acids with potential regulation of hepatic gluconeogenesis and insulin handling.

  • Increasing satiety and decreasing the energy density of the diet, making obesity less likely

  • Maintenance of insulin sensitivity, especially in the basal state. High carbohydrate diets tend to lower basal (fasting) glucose and insulin over several days. In turn, this decreases risk factors (hyperglycemia and hyperinsulinaemia) for cardiovascular disease.

  • Providing companion dietary compounds which tend to be protective of the cardiovascular system.